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Squid Proxy Cache Security Update Advisory SQUID-2023:9
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Advisory ID: | SQUID-2023:9
Date: | December 1, 2023
Summary: | Denial of Service
| in HTTP Collapsed Forwarding
Affected versions: | Squid 3.5 -> 3.5.28
| Squid 4.x -> 4.17
| Squid 5.x -> 5.9
Fixed in version: | Squid 6.0.1
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Problem Description:
Due to a Use-After-Free bug Squid is vulnerable to a Denial of
Service attack against collapsed forwarding
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Severity:
This problem allows a remote client to perform Denial of
Service attack on demand when Squid is configured with collapsed
forwarding.
CVSS Score of 8.6
<https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H&version=3.1>
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Updated Packages:
This bug is fixed by Squid version 6.0.1.
If you are using a prepackaged version of Squid then please refer
to the package vendor for availability information on updated
packages.
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Determining if your version is vulnerable:
Run the following command to identify how (and whether)
your Squid has been configured with collapsed forwarding:
squid -k parse 2>&1 | grep collapsed_forwarding
All Squid-3.5 up to and including 5.9 configured with
"collapsed_forwarding on" are vulnerable.
All Squid-3.5 up to and including 5.9 configured with
"collapsed_forwarding off" are not vulnerable.
All Squid-3.5 up to and including 5.9 configured without any
"collapsed_forwarding" directive are not vulnerable.
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Workaround:
Remove all collapsed_forwarding lines from your squid.conf.
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Contact details for the Squid project:
For installation / upgrade support on binary packaged versions
of Squid: Your first point of contact should be your binary
package vendor.
If you install and build Squid from the original Squid sources
then the <squid-users@xxxxxxxxxxxxxxxxxxxxx> mailing list is your
primary support point. For subscription details see
<http://www.squid-cache.org/Support/mailing-lists.html>.
For reporting of non-security bugs in the latest STABLE release
the squid bugzilla database should be used
<https://bugs.squid-cache.org/>.
For reporting of security sensitive bugs send an email to the
<squid-bugs@xxxxxxxxxxxxxxxxxxxxx> mailing list. It's a closed
list (though anyone can post) and security related bug reports
are treated in confidence until the impact has been established.
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Credits:
This vulnerability was discovered by Joshua Rogers of Opera
Software.
Fixed by The Measurement Factory.
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Revision history:
2022-09-03 18:41:32 UTC Patches Released
2023-10-12 11:53:02 UTC Initial Report
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END
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